Final answer:
Lightning strikes due to electrical charge differences, with negative strikes transferring electrons to positively charged areas. Cloud-to-cloud strikes indicate the struck area has a positive charge. Lightning rods prevent strikes by bleeding away induced charges, which can vary in strength based on cloud height.
Step-by-step explanation:
Lightning strikes are natural phenomena where a discharge of electricity occurs due to a buildup of electrical charge within a cloud relative to another cloud or the ground. A negative lightning strike happens when excess electrons from a negatively charged cloud are transferred to a positively charged area, such as the ground. In the case of a cloud-to-cloud lightning strike, the area hit by lightning would have a positive charge, as like charges repel and opposite charges attract.
Furthermore, lightning rods are devices designed to protect structures from lightning strikes by bleeding away the induced opposite charge continuously, which is created by the large charges in storm clouds. They work most effectively when pointed because a sharp point facilitates the discharge of the induced charge into the atmosphere, thereby preventing a direct lightning hit to the building.
To understand the impact of a lightning strike, considering the cloud-ground system as two parallel plates reveals that the energy of a lightning strike varies with the height of the clouds from the ground. The higher the cloud, the greater the potential for a lightning strike due to the larger potential difference created between the cloud and the ground.